function get(id)
	{
		return document.getElementById(id);
	}
	
	function oneToAnother(id)
	{
		if (id == "left")
		{	//取得左边的选中项的文本值
			var slt1 = get("left");
			var index = slt1.selectedIndex;
			var text = slt1.options[index].text;
			//从左边把这个选中的值删除
			slt1.remove(index);
			//往右边存放从左边移动过来的值
			var slt2 = get("right");
			var newOption = document.createElement('option');
			newOption.text = text;
			slt2.add(newOption);
			oneToAnother("left");
		}
		else if (id == "right")
		{
			//取得右边的选中项的文本值
			var slt1 = get("right");
			var index = slt1.selectedIndex;
			var text = slt1.options[index].text;
			//从右边把这个选中的值删除
			slt1.remove(index);
			//往左边存放从右边移动过来的值
			var slt2 = get("left");
			var newOption = document.createElement('option');
			newOption.text = text;
			slt2.add(newOption);
			oneToAnother("right");
		}
	}